1. Field of the Invention
The present invention relates to an unauthorized copy preventing system, an unauthorized copy preventing method, an unauthorized copy preventing program and a computer readable information recording medium, used for an image forming apparatus such as a digital copier.
2. Description of the Related Art
Recently, image forming apparatuses such as digital copiers have spread widely. As a reason thereof, performance of a digital signal processor (simply abbreviated as a DSP, hereinafter) mounted in such a type of image forming apparatus has been improved, and thereby, high speed and wide varieties of iamge processing can be achieved. Since variable image processing can be achieved as a result of a program or data being appropriately replaced in the DSP, a higher user friendliness is achieved in comparison to a case of applying an ASIC (application specific integrated circuit) (see Japanese Laid-open Patent Applications Nos. 8-274986 and 2001-76125, for example).
However, since image information is processed digitally in the DSP, modification/edition of the image information can be made easily, and, as a result, the image information may be applied for a wrong use (for example, unauthorized copy). Therefore, when the DSP for image processing is mounted in an image forming apparatus, it is necessary to consider a security system suitable for digital image information for the purpose of preventing unauthorized copy of an image.
As the security system in the related art, an art has been proposed in which, a specific pattern prepared for preventing copy is recognized during a process in which a DSP for image processing carries out image processing, and thus, unauthorized copy is avoided (see Japanese Laid-open Patent Application No. 2003-234894, for example).